Christini's design runs a pair of driveshafts, powered by a small gear on the rear wheel, through the bicycle's frame. A gear in the headset (where the handlebars meet the frame) transfers power to another driveshaft that runs down the fork and, in turn, attaches to a gear on the front wheel. The whole affair adds 2.7 pounds to the bike.
The bike's price is steep at $3,000 to $4,000(depending on the options you choose). But so are the hills you'll be able to climb when you click the all-wheel-drive button. By David Rocks